# Partial central diabetes insipidus during lithium use: A case report and literature review

## TL;DR

A 73-year-old man developed partial central diabetes insipidus possibly due to long-term lithium use, highlighting the need to consider this rare side effect.

## Contribution

This case report adds to the literature on rare central diabetes insipidus associated with lithium therapy.

## Key findings

- The patient showed symptoms of partial central diabetes insipidus despite long-term lithium use.
- Urinary osmolality did not increase sufficiently after water restriction, suggesting central rather than nephrogenic diabetes insipidus.
- Administration of vasopressin partially improved urinary osmolality, supporting a central etiology.

## Abstract

Nephrogenic diabetes insipidus (NDI) is a well‐known adverse effect of lithium, which occurs in approximately 20%–40% of long‐term lithium users. Although rare, there have been reports of central diabetes insipidus (CDI) associated with lithium use. Herein, we report a patient with suspected CDI associated with chronic lithium therapy. Furthermore, we conducted a literature search for cases with CDI and discuss the pathogenesis of this case based on previous reports.

The patient was a 73‐year‐old man with bipolar disorder Type I. His psychiatric symptoms had been stable for many years. However, polyuria and weakness began to appear at the age of 73. Initially, lithium‐induced NDI was suspected, but in the end, partial CDI was suspected because urinary osmolality did not exceed 300 mOsm/L even after water restriction, and administration of nasal arginine vasopressin solution partially increased urinary osmolality.

We have experienced a case in which CDI may have been induced by lithium. Although the effects of ageing and infection cannot be ruled out, it should be noted that when lithium‐induced diabetes insipidus is suspected, CDI may also occur depending on the clinical context.